Userscripts.org

Chrome until it does not support, but you can use bookmarklet for blocking (select code and drag-n-drop it on bookmark bar):

javascript:(function(){if(window.navigator.ujs_AdBlock)return;else window.navigator.ujs_AdBlock=true;var f='',outline='',title='',bgColor='',frameBorder='',altPressed=false;var g=function(a){var b=a+'=';var d=document.cookie.split(';');for(var i=0;i<d.length;i++){var c=d[i];while(c.charAt(0)==' ')c=c.substring(1,c.length);if(c.indexOf(b)==0)return unescape(c.substring(b.length,c.length))};return''};var h=function(a,b){var c=new Date();c.setTime(c.getTime()+(10*365*24*60*60*1000));if(document.cookie.length<3000)document.cookie=a+'='+escape(b)+'; expires='+c.toGMTString()+'; path=/';else alert('Cookies is full!')};var k=function(a){var s=document.createElement('style');s.setAttribute('type','text/css');s.setAttribute('style','display: none !important;');s.appendChild(document.createTextNode(a));return(document.getElementsByTagName('head')[0]||document.documentElement).appendChild(s)};var l=function(b){var a=b.split(',');for(var i=a.length-1;i>=0;i--){var c=a[i]+' > ';for(var j=a.length-1;j>=0;j--){if(a[j].indexOf(c)==0)a.splice(j,1)}};return a.join(',')};var m=function(b){var c='';for(var i=0,a;a=b.attributes[i];i++){var n=a.nodeName.toLowerCase();if(/^(id|class|height|width|color|href|src)$/.test(n))c+='['+n+'=\x22'+a.nodeValue+'\x22]'};return c};var o=function(a){if(altPressed||/^(html|body|iframe|img|a)$/i.test(a.nodeName))return'';var b,n=0;var p=a.parentNode;for(var i=0,c;c=p.childNodes[i];i++){if(c.nodeType==1){n++;if(c==a)b=n}};return(!b||n<2)?'':':nth-child('+b+')'};var q=function(a){var b='';if(a.hasAttribute('src')){b=a.nodeName+'[src=\x22'+a.getAttribute('src')+'\x22]'}else{var c=[];while(a){if(a.nodeType==1)c.unshift(a.nodeName+m(a)+o(a));a=a.parentNode};b=c.join(' > ')};var d=k(b+'{background-color: #FF5555 !important; outline: 1px solid #FF1111 !important; opacity: 0.7 !important;}');b=prompt('Block this element(s)?',b);if(b){k(b+'{display: none !important;}');var e=g('ujs_adblock');h('ujs_adblock',(e?l(e+','+b):b))};d.parentNode.removeChild(d)};var r=function(){document.removeEventListener('mouseover',t,false);document.removeEventListener('mouseout',u,false);document.removeEventListener('click',v,false);document.removeEventListener('keyup',w,false);delete window.navigator.ujs_AdBlock};var t=function(a){f=a.target;outline=f.style.outline;title=f.title;bgColor=f.style.backgroundColor;frameBorder=f.frameBorder;if(frameBorder)f.frameBorder=1;f.style.outline='1px solid #306EFF';f.style.backgroundColor='#C6DEFF';f.title='Tag: '+f.tagName+(f.id?', ID: '+f.id:'')+(f.className?', Class: '+f.className:'')};var u=function(){if(f){f.style.outline=outline;f.title=title;f.style.backgroundColor=bgColor;if(frameBorder)f.frameBorder=frameBorder}};var v=function(a){if(f){altPressed=a.altKey;a.preventDefault();u();r();q(f)}};var w=function(a){if(a.keyCode==27){u();r()}};document.addEventListener('mouseover',t,false);document.addEventListener('mouseout',u,false);document.addEventListener('click',v,false);document.addEventListener('keyup',w,false)})();

Looks as known Chrome bug: http://code.google.com/p/chromium/issues/detail...

> If cookies is full, i cannot edit styles (Alt+E)
Fixed.